I just downloaded a lovely pattern for lace curtains, but am unsure about how to go about substituting the yarn. I just moved to Seoul and haven't found knitting shops that carry the brands I'm used to. Also, the gauge in the pattern is measuring post-blocking so I'm not sure what to do...

Possibly heavy crochet thread would work. If the gauge of whatever you use is off, the curtains may be wider or narrower than you need, so you should dec the number of sts if you need to fit a certain size.